The goal of this project is to understand the inhibitory and development effects of lipophilic acids, including preservatives, antiseptics and various drugs. Some of these compounds are known or suspected to casue brain damage or to be teratogens. 1) The partition coefficients and pK values of some of the compounds were determined and correlated to the inhibitory potency on Bacillus subtilis and mammalian cell lines such as HeLa, glial cells, and fibroblasts. Compounds with high (octanol/water) partition coefficients and high electron delocalization are most inhibitory. The results allow predications as to which frequently employed lipophilic acid is most likely to be teratogenic or cause postnatal damage. 2) Fatty acids cause a change in the membrane microviscosity of mammalian cells, but this effect is not related to the morphological alterations caused by butyrate. 3) Investigations with a mutant HeLa have shown that butyrate exerts its effect only if it can be metabolized. 4) The capability of inducing Beta-adrenergic receptors in cultured human cells has permitted us to define four components involved in the transmission of a neurotransmitter's signal across the plasma membrane.